#!/usr/bin/env python
# -*- coding: utf-8 -*-

# ***************************************************************************
# *   Copyright (C) 2024, Paul Lutus                                        *
# *                                                                         *
# *   This program is free software; you can redistribute it and/or modify  *
# *   it under the terms of the GNU General Public License as published by  *
# *   the Free Software Foundation; either version 2 of the License, or     *
# *   (at your option) any later version.                                   *
# *                                                                         *
# *   This program is distributed in the hope that it will be useful,       *
# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
# *   GNU General Public License for more details.                          *
# *                                                                         *
# *   You should have received a copy of the GNU General Public License     *
# *   along with this program; if not, write to the                         *
# *   Free Software Foundation, Inc.,                                       *
# *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
# ***************************************************************************

import math, cmath, datetime, time

from gnuradio import soapy
from subprocess import Popen, PIPE

def open_hackrf(freq_hz,amp_enable,gain_db,samplerate_hz,clock_correction_hz):
  proc = Popen(
    ["hackrf_transfer",
    "-t",
    "-", # i.e. stdin
    "-f",
    str(freq_hz),
    "-a",
    str(amp_enable),
    "-x",
    str(gain_db),
    "-s" ,
    str(samplerate_hz),
    "-C",
    str(clock_correction_hz)],
    stdin=PIPE,
    stdout=PIPE,
    stderr=PIPE
    )
  return proc

def transmit(
    pipe,
    mode,
    mf, # modulation frequency Hz
    md, # modulation depth, 1.0 = 100%
    duration_sec,
    numsamples
    ):
  t = 0
  dt = duration_sec / float(numsamples)

  match mode:
    
    case 'cw':
      for _ in range(numsamples):
        c = 2 * math.pi * t
        # generate cos(x), i sin(x)
        v = cmath.exp(complex(0,c)) * 128
        i = int(v.real) % 256
        q = int(v.imag) % 256
        pipe.write( bytes([i,q]))
        t += dt
        
    case 'am':
      for _ in range(numsamples):
        c = 2 * math.pi * t
        # modulation value * modulation depth
        mv = ((1.0 + math.cos(c * mf) * md) * 0.5)
        # generate cos(x), i sin(x)
        v = cmath.exp(complex(0,c)) * 128 * mv
        i = int(v.real) % 256
        q = int(v.imag) % 256
        pipe.write( bytes([i,q]))
        t += dt
      
    case 'fm' | 'wfm':
      deviation = (0.2,0.012)[mode=='fm']
      fmi = 0.0 # frequency modulation integral
      for _ in range(numsamples):
        c = 2 * math.pi * t
        # modulation value * modulation depth
        mv = math.cos(c * mf) * md
        # update FM modulation integral
        fmi += mv * deviation
        v = cmath.exp(complex(0,c + fmi)) * 128
        i = int(v.real) % 256
        q = int(v.imag) % 256
        pipe.write( bytes([i,q]))
        t += dt
    case _:
      print(f'Error: no mode "{mode}".')

def main():
  # high_output = True : antenna connections
  # high_output = False : direct wired connections
  high_output = False

  if high_output:
    amp_enable=1
    gain_db=45
  else:
    amp_enable=0
    gain_db=0

  samplerate_hz = 2000000 # 2 MHz

  # tested 2024.03.14, closest integer
  clock_correction_hz=-6

  duration_sec = 2 # seconds

  numsamples = int(samplerate_hz * duration_sec)

  freq_mhz = 3.0 # base frequency MHz

  freq_hz = freq_mhz * 1e6
  
  mode = 'am'
  
  mf = 440 # modulation frequency
  md = 1.0 # modulation depth, 1.0 = 100%

  start = datetime.datetime.now()
  
  proc = open_hackrf(freq_hz,amp_enable,gain_db,samplerate_hz,clock_correction_hz)

  pipe = proc.stdin

  transmit(pipe,mode,mf,md,duration_sec,numsamples)

  # must terminate hackrf process
  proc.terminate()
    
  end = datetime.datetime.now()

  print(f"Generation time: {end-start}")

if __name__ == '__main__':
  main()